A test for comparing the means of two samples, or the mean of one sample (or even parameter estimates) with a specified value; also known as the "Student t-test" after the pseudonym of its inventor.

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Basic methods for detecting outliers

Let $X$ be a matrix of $n$ rows and $m$ columns. $n$ is the number of samples and $m$ is the number of gene expressions. Gene expressions are basically numerical continuous values. Assume we have a ...
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14 views

Can I compare three averages if no independent variable?

I am not used to this type of data, and am not experienced with statistics so am really getting hung up. This is an undergraduate research project. I have done a total fecal collection on 12 horses. ...
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11 views

What Statistical Test of Significance is Suited to Comparing Two Classes of Students on Volume of Access?

I'm an educator and I'm delving a little further into stats than I normally would to try to determine how effective a new teaching method is. I'd really appreciate some advice on the best approach to ...
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2answers
10 views

Methods for compiler benchmarking?

In computer science, statistical knowledge is quite low in general. You rarely see standard deviation in papers. Now I am trying to improve at least my skills, but I find myself utterly confused about ...
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1answer
17 views

One-tailed vs. two-tailed t-test and P level

In a two-tailed t-test for a P of 0.1 and a one-tailed test for a P of 0.05, is the t value to show significance the same? I understand that the two-tailed test is looking for significance at either ...
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1answer
18 views

How to compare two Bayesian networks?

I have two different datasets on which I've applied the same learning (K2) algorithm to learn a Bayesian network. I have the conditional probability table (CPT) of the class variable, for each of the ...
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18 views

Metaphors for understanding t-test? [closed]

Does anyone know of any metaphors or analogies that make understanding the t-test easier?
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33 views

Which is the best statistical test for assessing the quality of a prediction?

I have a function that I'm trying to modulate and I would like to have a statistical indicator that inform me how good / poor my prediction is. In the image below, I show the function (...
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1answer
25 views

Paired permuted t-tests?

I have a small dataset which are not normally distributed. I would like to perform a pairwise analysis of the differences in values between two groups. It has been suggested that I use permuted ...
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1answer
127 views

Significant t-test results accurate or random?

I've performed a bunch of independent t-tests looking for a relationship between 10 different variables in group A and 10 different variables in group B. There seems to be very few significant ...
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1answer
18 views

Comparison of mean values between two periods

An authority has decided to legislate on stricter rules regarding amortization. The previous legislation stated that a mortgage loan has to be amortized down to a degree of at least 75% of the price ...
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16 views

What's the most appropriate statistical treatment or test for my study? [closed]

I'm to correlate the effect of age, gender and year level to the preference of students to computer specification. its just that there are different age brackets and year level, how am I suppose to ...
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19 views

Multiple T-Test with Trended Data in R

I am having issue getting the p-values from a T-Test for a 'typical trended study'. The aggregated values for satisfaction by months are the following. ...
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18 views

Independent t test significant but post-hoc planned analysis not

I was analysing two sets of data. In most cases for the study post hoc planned comparisons identified significance (<0.05), however for one sample, this was not achieved. However an independent t ...
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1answer
12 views

paired samples (t-test?) with grouping variable

Im trying to determine the correct analysis for paired data with a grouping variable. I have 3 fish in each of 4 treatments, so 12 fish in total. Treatments are that the fish are fed at one of four ...
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0answers
19 views

How to identify items answered differently by some factors such as male vs. female?

I want to do something like this: Variable: students (undergraduate, master students, and PhD students) Research instrument: XXXX (20 items) Reporting: The ANOVA analysis suggested that there is no ...
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1answer
43 views

Testing for mean statistical difference in segments of different length in the same Time Series

I have a Time Series of 336 monthly observations, from January 1987 to December 2014. I'd like to test for differences in uneven (of different size) segments of this time series. In effect, it would ...
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13 views

Bootstrapping for semi-independent, non-normal population

I want to test whether or not there is a difference in mean productivity between two categories in an ordinal ranking system. The productivity data I've collected is for a series of 3 year windows ...
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19 views

Tests of Normality using tool developed by CFA

I am doing a paired sample t-test pre/post intervention. I have used a tool where psychometric analyses included confirmatory factor analysis (CFA) and item response theory. For my data tests show ...
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1answer
42 views

t test vs. F test

In linear regression, I have heard that the t test is more versatile than the F test because the t test can test the null hypothesis $H_0:{\beta_1}=k$ for $k$ a constant, whilst the F test can only ...
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19 views

Comparing 2 insignificant p-values

I've run two t-tests, and the p-value of each is a=0.3 and b=...
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11 views

(Pretty) large sample size, unequal variance, unequal sample sizes, non-normal distribution. T-test alternative?

So, I've never had all these problems at the same time before, but I have: - Likert data, from a 9 point scale - n = 317 v 177 respectively - SD = 2.08 v. .274; 1.9 v. 2.6; 2.5 v. 2.9 etc. (you get ...
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19 views

Other statistical tests for paired data

Are there other statistical tests available to compare paired sets of data e.g. {1, 2, 2, 3, 4} v's {3, 3, 3, 2, 5} for similarity, aside from the paired Wilcoxon and paired Student t-test?
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1answer
36 views

Multiple T Tests

On one of my questionnaires, which measure learning behaviours, after PCA, I have 4 subgroups, Efficacy/Perseverance/Effort/Achievement - I have run a T-Test and I have 4 sets of data comparing my ...
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1answer
59 views

Do the different levels of treatment in a completely randomized design come from different population?

Suppose in a completely randomized design , a treatment A have four levels. When we check whether the means of four levels are statistically significant ,i.e., $$H_0:\mu_1=\mu_2=\mu_3=\mu_4$$ ...
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31 views

How is T-test identical to ANOVA?

I wondered if I need to use T-test or ANOVA in case of testing two groups for their mean equality and got a response that these two tests give identical results. I have checked, running experiments, ...
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6 views

Is there a t-test equivalent to Stouffer's z-test?

I have k pairs of samples from different distributions. For each pair of samples I want to check if the samples are taken from a normal distribution with the same mean and variance. I assume the ...
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1answer
38 views

What is a t-test and how is it used in relation to animal physiology? [closed]

How do you find the confidence level and P value in a t-test? For example, how would you use these variables to compare Daphnia heart rates and their circulatory activity?
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1answer
23 views

T-test on percentage values (among experimental replicate values)

My experiment involves looking at the precentage of cells in a slide that have a particular property under condition A and condition B. I have one slide for each condition. I have done this experiment ...
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16 views

Multilevel version of one-sample t-test

I have a question about a multilevel model in which I model correct predictions made for a coin toss. Correct prediction are given 1 and incorrect 0. Since the coin toss is random, correct predictions ...
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19 views

How to determine correct statistical test for repeated measures, differing treatments in same subject experiment

Our hypothesis is that treatment 1 changes our outcome measure by some amount, and that treatment 1 combined with treatment 2 changes our outcome measure by a larger amount. For each subject, the ...
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3answers
122 views

“The test statistic is reported as a z…”

I was reading a neuroimaging paper in which the authors compare the effect of a chemical compound on a measure of brain connectivity. They measure the value of connectivity for each brain voxel under ...
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24 views

Central limit theorem: applicability for assumptions of different tests

Since many statistical procedures (e.g. t-test, ANOVA, Pearson’s r (for efficient estimates)) require the normal distribution of the tested variables ('normality-assumption') one may ask if (at least) ...
3
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1answer
38 views

How to test paired observations

I have a set of data that look like this: ...
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31 views

paired t-test for pairs each having more than one sample

I have a large and a small data set (the small data set is a subset of the large data set) with 2 columns(lets say var1 and var2). Now, based on var1 in the data set, I have sorted the large data set ...
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11 views

t-test : how to recover alpha when only have t-stat and Dof

In a t-test, is it possible to recover the value of alpha when you only have the degrees of freedom and the t-statistic? e.g. qt(0.05/2,100) = -1.983972 If I know that dof=100 and that ...
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6 views

Formula behind variables importance in linear model with caret library

The caret library can measure the importance of predictors http://topepo.github.io/caret/varimp.html The importance for a Linear Models is computed as: 'the absolute value of the t-statistic for ...
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15 views

Two experiments with shared control, can I generalize?

I have run two experiments, let's say the control condition is A. The two treatment conditions are B and C. I determined that B < A on some variable, and that C > A on that same variable. These ...
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1answer
59 views

Testing correlation and the t-statistic used in Simple Linear Regression

Given $H_0$ : $\rho=0$ and $H_A$ : $\rho\neq0$, we use the test statistic $t_{n-2}$ , which is $\frac{r\sqrt{n-2}}{\sqrt{1-r^2}}$. I have to show that $\frac{r\sqrt{n-2}}{\sqrt{1-r^2}}$ equals ...
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2answers
54 views

Comparing data that has been recorded on two devices

I have two data loggers which are recording a physiological signal. Device A is a system that has been in place for many years, and records data ~once/minute. Device B is a prototype device which ...
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12 views

Using LIWC for ANOVA and pairwise analyses

I want to use a tool called Linguistic Inquiry and Word Count (LIWC) to analyze text data. As far as I know, it counts the number of words found in a given text that match a set of dimensions (e.g., ...
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9 views

extracting t value out of pairwise.t.test [migrated]

I would like to know if I could extract t values out of the pairwise.t.test function since it is only reporting the p values. I used the pairwise.t.test() for multiple comparisons after running a ...
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2answers
72 views

This is purported to be a paired t-test - I doubt it [closed]

This is the problem: Some nerve cells have the ability to regenerate. Researchers think that these cells may generate creatine phosphate (CP) to stimulate new cell growth. To test this ...
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46 views

How to compare three groups to one control group without assuming equal variances?

I need to determine if one dependent variable (tensile strength) for each of three new groups is equivalent to that from my original ("control") group. I am not concerned with how the three new groups ...
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1answer
32 views

Comparison of two means within the same group

I created a pretest before my main study. The goal of the pretest is to find two brands that are equal in terms of liking and familiarity. I computed the variables in SPSS and I was wondering if I ...
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44 views

Compare more than two means

New in statistics and I need your help regarding an easy question I think. I'm running out of time for my assignment so I kindly ask you to help me if possible. I'm running a pretest and the main ...
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0answers
27 views

Mann Whitney or t test?

I have 4 questions which ask different branches of the same topic (I suppose they are related to each other). Different numbers of people responded to each question. They responded to each question by ...
2
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2answers
47 views

When to create a control group with paired T test

So if I wanted to measure the effect of a drug on a group of people, I think I would use a paired T test based on my research. But what if something caused a change in my group that I did not account ...
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26 views

Is the increase in Type I errors due to multi-sample t-tests overstated?

To illustrate, let's say you want to compare the means of 3 samples with t-tests. You would then have to run 3 tests to compare the means of each possible combination of samples. The explanations I ...
3
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1answer
41 views

Statistics on tastings

Some people at my workplace have had some fun lunch discussion as of late, concerning some people's alleged ability to taste the difference between things one thought one shouldn't be able to taste a ...